1. Field of the Invention
The present invention relates to aqueous dispersions or solutions of compounds, which contain alkoxysilane and/or silanol groups and are substantially free from isocyanate groups and chemically incorporated hydrophilic groups, and to their use as binders for coating, adhesive or sealant compositions.
2. Description of the Prior Art
Compounds containing urea or hydantoin groups and also containing alkoxysilane groups are known and disclosed in U.S. Pat. Nos. 5,756,751 and 5,364,955 and in copending application, U.S. Ser. No. 08/814,561. The presence of alkoxysilane groups in these compounds can be used to improve the adhesion and chemical resistance properties of coatings when compared to those prepared from the known polyurethane resins. One of the disadvantages of these compounds is the need to blend them with organic solvents in order to reduce their viscosity for certain applications.
Copending applications, U.S. Ser. Nos. 08/992,163, 08/992,551 and 09/057,675, disclose that it is possible to reduce or eliminate the need for organic solvents by dispersing the compounds containing alkoxysilane groups in water. However, in order to render these compounds water dispersible it is necessary to hydrophilically modify these aqueous compositions by chemically incorporating ionic and/or non-ionic hydrophilic groups and optionally by the use of external emulsifiers.
While the presence of the hydrophilic groups improves the compatibility of the urea/hydantoin compounds with water, it also makes the coatings, adhesives or sealants prepared from these compounds more sensitive to water or moisture. In particular, the water resistance of the resulting products is reduced and the amount of water swelling that the products undergo in the presence of water is increased.
Accordingly, it is an object of the present invention to provide aqueous compounds containing alkoxysilane and/or silanol groups that do not suffer from the deficiencies of the prior art compounds, i.e., water can be used to replace all or at least a portion of the organic solvent and the compounds can be rendered compatible with water without the use of the known ionic and/or non-ionic hydrophilic groups.
This object may be achieved with the aqueous compounds according to the invention which are described in detail hereinafter. It has been found that these compounds can be dispersed in water without the need for the known hydrophilic groups.